Such a seat hinge mechanism is known, for example from document FR2977204.
It is desirable to be able to reduce the locking pitch in order to provide an increased number of possible tilt adjustment positions, improving the comfort for seat occupants; in particular, we want to obtain a locking pitch of less than 1.5 degrees or preferably less than 1 degree.
The teeth of these elements usually have a generally triangular profile.
The solution that consists of increasing the number of teeth faces a basic problem of geometry, because as the number of teeth increases the depth of the teeth decreases and therefore the depth of the engagement decreases as well. However, safety requirements call for maintaining the seat position during a collision involving the vehicle, which implies a relatively extensive engagement between the teeth of the movable elements and the base gear teeth of the plate, in order to guarantee robustness during a collision.
There is therefore a need for a solution that provides a smaller locking pitch while continuing to meet safety requirements concerning the hinge mechanism between the backrest and seat cushion.